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An investigation is presented of the explosion of a CNG (compressed natural gas) fuel vessel, called a liner, in an urban bus. The explosion happened at a gas station 10 min after filling was completed. There were no traces of soot and flames at the failed liner, which would be indicative of explosion by ignition of the gas. The filling process of the station was automatically monitored and recorded in a computer. There was no unusual record of the filling system that indicated excess pressure at the time of the accident. There were cracks on the liner that were initiated at the outer surface of the cylindrical shell located at a point 4 cm above the lower dome where cracks did not originate easily as a result of overload. Chemical analysis was performed on a specimen that was cut from the liner, and there was no peculiarity in the mix. Mechanical analysis was performed on the specimens and showed that the hardness was not in the specified range because of inadequate heat treatment of the metal. The hardness of the liner was strictly controlled in the manufacturing process. All the liners that were manufactured at the same period with the failed liner were recalled for examination.

[formula: see text] A novel pentacyclic polyhydroxylated sterol, xestobergsterol A (1a), has been synthesized in 24 steps and in good overall yield from stigmasterol 17. The key steps of the synthesis are the Breslow remote functionalization of the polyoxygenated steroid derived from 25 and the base-catalyzed epimerization-aldol condensation of the dione derived from 27.

[formula: see text] The synthesis of all four diastereomers of bis(propionates), 3,5-dialkoxy-2,4-dimethylalkanals, by non-aldol aldol chemistry is described. The epoxy alcohols (3, 4) were converted into the mesylates (9, 11) which were cleanly rearranged to the desired 3,5-bis(oxygenated)-2,4-dimethylalkanals (10, 12) in high yield. The epoxy mesylates (13, 16) gave the desired products (14, 17) in good yield on treatment with TMSOTf and a hindered base.

This study investigated sex differences in responding to the pentylenetetrazol (PTZ, a gamma-aminobutyric acid A antagonist) discriminative stimulus and to substitution to PTZ during ethanol withdrawal. The PTZ stimulus has served as an anxiogenic stimulus in numerous studies. Adult male and female rats were trained to discriminate PTZ (16 mg/kg i.p.) from saline in a two-lever food-reinforced task. They were then gonadectomized or sham-operated. Ovariectomized (OVX) rats were also tested during 17beta-estradiol (2.5 mg, 21 days release, s.c.) replacement. The PTZ dose response (0-16 mg/kg i.p.) was tested in all groups. In general, fewer females than males responded to PTZ. Diazepam (DZP; 0-10 mg/kg i.p.) injected before PTZ (16 mg/kg) decreased the number of rats selecting the PTZ lever. This effect was greater in sham female and estradiol-replaced-OVX rats than in male or OVX rats. Rats then received chronic ethanol diet (6.5%) for 10 days. During ethanol withdrawal (12 h after termination of the ethanol diet), they were tested for PTZ lever selection. PTZ lever selection differed between groups: sham or castrated male ratsOVXsham female or estradiol-replaced-OVX rats. In sham female rats, estradiol concentrations showed a cyclic pattern with an estradiol surge that did not influence their PTZ discrimination performance. After i.p. injection of ethanol (2 g/kg), blood ethanol concentrations were not different in male and female rats. These findings suggest that 1) female rats are less sensitive to the anxiogenic effects of PTZ; 2) female rats are less sensitive to the anxiogenic effects of ethanol withdrawal; and 3) estrogen plays some role in mediation of these sex differences.

When ethanol is used as a training stimulus in drug discrimination experiments, benzodiazepines (such as diazepam) as well as non-competitive N-methyl-D-aspartate (NMDA) antagonists (such as ketamine) substitute for ethanol; in contrast, when a benzodiazepine or an NMDA antagonist is used as a training drug, ethanol does not substitute reliably. In the present experiments, we trained rats to discriminate a mixture of diazepam and ketamine, to test the hypothesis that ethanol would substitute for this drug combination. Using a two-lever choice procedure with food as a reinforcer, 22 rats were trained to discriminate a mixture of diazepam (5.6 mg/kg) and ketamine (10 mg/kg) from vehicle. When administered as a mixture, diazepam and ketamine substituted for the training mixture in a dose-dependent manner. When administered separately, diazepam or ketamine substituted for the mixture with full substitution occurring at 5.6 and 17.8 mg/kg, respectively. Ethanol almost completely substituted for the mixture at 1 g/kg. There was no cross-substitution between diazepam and ketamine in rats trained to discriminate diazepam (5.6 mg/kg, n = 10) or ketamine (10 mg/kg, n = 12) from vehicle. In addition, ethanol did not substitute for the training drug in either of these discriminations. These results suggest that the simultaneous action of GABAA agonist and NMDA antagonist mechanisms produce a greater ethanol-specific discriminative stimulus than activation of either component individually.

This study was conducted to investigate the p53 gene alterations in 25 surgically-resected gastric adenocarcinomas in the Korea Cancer Center Hospital by polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) for exons 4-8 and immunohistochemical staining (IHCS) with anti-p53 antibody, DO-7. p53 mutations were detected in nine (36%) out of 25 cancer tissues by PCR-SSCP in exon 4-8: 0,1,1,6 and 1 mutations in exons 4,5,6,7 and 8, respectively. All tissues were also tested by IHCS, and positive staining was observed in 11 cases (44%). A discrepancy of the results between the two methods was observed in four cases. In one which showed positivity by PCR-SSCP a negative reaction by IHCS, the two base deletion was observed in exon 7. On the other hand, in three cases the mutation was detected only in IHCS but not in PCR-SSCP. The exact mechanism by which this discrepancy develops is not clear at present, although it may be due to the mutation of other exons not tested in this study or the relatively low sensitivity of the PCR-SSCP method. The incidence of p53 gene mutations was analysed according to pathologic stage and histological differentiation, but no significant difference was observed between the p53 alterations and these factors. By combined use of PCR-SSCP and IHCS, 48% of the 25 primary gastric cancer were considered to have mutations of the p53 gene. These results suggest that p53 mutation is not an infrequent event in primary gastric cancer and the p53 gene plays an important role in the carcinogenesis process of gastric cancer.